DIRECT AGGLUTINATION OF WEAK D RED-CELLS BY TETRAMOLECULAR COMPLEXES CONTAINING MONOCLONAL IGG ANTI-D

The capacity of blood group antibodies to agglutinate red cells suspen ded in saline is largely dependent on the antibody isotype. The immuno logical cross-linking of IgG antibodies has previously been described as a means to increase the reactivity of IgG in many situations. We ha ve prepared anti-D-containing complexes by blending a human IgG anti-D monoclonal antibody (mAb) and a murine anti-human IgG mAb. In standar d red cell serology assays, the anti-D complexes exhibited a very high avidity and could agglutinate weak D-positive red cells in direct sal ine testing. These results indicate that potent saline hemagglutinatin g reagents of RhD and eventually of other blood group specificities ca n be prepared from IgG mAbs.